CAMPAIGNERS for Scottish independence suffered a fresh blow today as banking giants confirmed plans to relocate south of the border.

The Royal Bank of Scotland (RBS) announced it would relocate its headquarters to London in the event Scots vote to break off from the UK next week.

In an internal letter, the bank – which has been based in Scotland since 1727 – said the move would not affect the 3,000 Scots employed by the company but was instead "a technical procedure regarding the rotation of our registered head office based on our current strategy and business plan".

Despite this reassurance, the news came as a blow to the 'Yes' camp, who were last night also hit by a new poll showing a six-point lead for the 'No' campaign.

Following RBS, Lloyds Banking Group also confirmed it is set to shift departments south of the border – including its legal home – into the company's headquarters, already located in London.

The banks' decision later sparked a row between First Minister Alex Salmond and the BBC.

Claiming the news was part of a Westminster-led plot to upset the Scottish vote, Mr Salmond became embroiled in a heated discussion with BBC political editor Nick Robinson - whom he accused of "heckling" - at a press conference.

Mr Salmond has revealed he has written to the Cabinet Secretary to demand an investigation into the apparent leaking of "market sensitive information" about RBS.

The first news of this came to the BBC from a source within the UK Government, within the Treasury, not from the letter from the chief executive issued this morning which makes clear there's no impact on operations or jobs

Alex Salmond

Speaking earlier, he said: "The first news of this came to the BBC from a source within the UK Government, within the Treasury, not from the letter from the chief executive issued this morning which makes clear there's no impact on operations or jobs.

"It's part of a political campaign during this referendum campaign from the UK Government."

The Scottish National Party leader has previously accused the 'No' campaign of "scaremongering" as a "deliberate tactic" in the campaign.

He added: "My submission and my confidence is that the people of Scotland have moved beyond this sort of intimidation and know that Scotland can be a prosperous and successful country."

Meanwhile, a leading retailer has warned Scots they face higher prices if they vote for independence.

The boss of John Lewis Partnership, which has nine shops and a contact centre employing over 3,000 people in Scotland, cautioned shoppers.

Chairman Sir Charlie Mayfield said: "The debate has clearly become very, very fractious. As a businessman it is not my place to tell Scottish voters how to vote in next week's referendum.

"On the day after the referendum the shops are going to open on time, nothing will change.

However, he went on to confirm there would be "economic consequences to a Yes vote" because "for various reasons - regulation and transport costs etc - it does currently cost more money to serve parts of Scotland."

Sir Charlie revealed his firm were unlikely to continue sharing the burden of higher operating costs in Scotland across all UK customers in the event of the break up of the Union.

Former chief executive of Sainsbury's Justin King also warned that an independent Scotland would increase costs for supermarkets.

However, Tesco has dismissed claims by the pro-UK 'Better Together' campaign – stating that claims their prices would have to increase are “entirely speculative”.

Deputy Prime Minister Nick Clegg accused Mr Salmond of being "almost comic" in his repeated inability to answer the 'Better Together' campaign's questions on finance and business, during an LBC phone-in this morning.

The Deputy Prime Minister said: "I think he has been living and breathing this all his life. It's his life's mission but just because something is someone's life mission doesn't mean the mission is the right thing for the people he seeks to represent.

"It is becoming almost comic the way you have major, major figures raising massive alarm bells about the economic consequences of independence.

"Just this morning the head of John Lewis saying prices would go up for shoppers in Scotland and then the SNP said 'oh, he's exaggerating'. BP, they say please don't go independent, 'oh, they're exaggerating'."